180 KJELLMAN, THE ALG OF THE ARCTIC SBA. 
and, above all, by the middle cells of the main axis and the long branches being only 
half as long as in the latter. It can hardly be a distinct species. The length of the 
cells is subject to variation. Nevertheless I have thought fit to record it at present 
under a special name. 
Habitat. Those few individuals, which | have myself collected, grew in 10—15 
fathoms water, attached to Lithothamnion soriferum. On the coast of Greenland it 
appears to be litoral, as J. Vani has noted on the label belonging to it »inter cxspites 
Gigartine subfusca», From the Polar Sea it is known only as sterile. 
Geogr. Distrib. Found in the Norwegian Polar Sea and Baflin Bay. Its northern- 
most locality is Gjesver on the north coast of Norway, Lat. N. about 71°. 
Localities: The Norwegian Polar Sea: Finmarken at Gjesveer. 
Baffin Bay: the west coast of Greenland at Julianeshaab and Godhavn, according 
to specimens in the herbarium of the Copenhague Museum. 
Antithamnion boreale Gost (nob.) 
Antithamnion plumula var. boreale Gopi, Algenfl. Weiss. Meer, p. 47. 
f. typica nob. 
Descr. Antithamnion plumula var. boreale Gost, |. ec. p. 47 et sequent. 
Fig. » boreale f. typica tab. nostra 16, fig. 2, 3. 
f. lapponica Rurr. (nob.) 
Descr. Callithamnion lapponicum Rupr. Alg. Och. p. 343. Cfr. Gopi, Algenfl. Weiss. Meer. p. 48—49 sub A. 
plumula var. boreali. 
f. corallina Rurr. (nob.) 
Deser. Callithamnion corallina Rupr. Alg. Och. p. 340—341. 
Antithamnion corallina KjeLbM. Algenv. Murm. Meer. p. 24. 
Fig.  Antithamnion boreale f. corallina Tab. nostra 16, fig. 4, 5. 
Syn. Antithamnion corallina Ksetum. Algenv. Murm. Meer. p. 24. 
» plumula KyeLim. Vinteralgv. p. 64; Spetsb. Thall. 1, p. 26; Algenv, Murm. Meer. 
p- 24; Kariska hafvets Algv. p. 23. 
» KEEN, Nordl. Alg. p. 21. 
Callithamnion corallina Rupr. 1. c. 
» lapponicum Rupr. 1. ¢. 
» plumula J. G. Ac. Spetsb. Alg. Progr. p. 2; Bidr. p. 11. 
Remark on the determination of the species and its forms. I have mentioned already 
in my account of the Floridexw of Spitzbergen, that the plant collected here which I 
named Antithamnion plumula in accordance with J. G. AGARpu, differs in certain respects 
from the southern species of that name. I have found later in the eastern Murman 
Sea and in the Kara Sea a form resembling that from Spitzbergen, and, besides, in 
the first-mentioned sea another form that I have considered and still consider identical 
with Ruprecut’s Callithamnion corallina. Gost has subsequently, in his account of the 
marine Flora of the White Sea, made a detailed and most excellent exposition of the 
arctic alg that are most nearly related to Antithamnion plumula. He proves the form 
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L~4ea. 
